1. Technical Field of the Invention
The invention relates generally to wireless communication systems and the transmission of video data; and, more particularly, it relates to power and other cost saving techniques based on detection of static portions of a video stream.
2. Description of Related Art
Many approaches have been developed for improving power consumption and error robustness/concealment when transmitting video data. For example, power efficiency in a wireless video network delivering video packets may be improved by adaptively modifying the transmission power level of a wireless access point based upon device proximity data, wireless channel conditions, reception characteristics and the like. With respect to error concealment, network layer solutions may be utilized that attempt to recover the error/packet loss at the packet layer in order to provide an error free A/V stream to a receiver and its video decoder. Such solutions usually require redundant codes and retransmissions that may lead to increased power consumption in certain operating environments. Video layer solutions may also be employed, including post-processing that accepts a corrupted video stream and tries to mitigate gaps and mismatches in the decoded video frames.
As may be understood, network layer solutions and video layer solutions each involve tradeoffs. In particular, a heavily protected network layer might be very robust and resilient to errors, but usually this is accompanied by a reduction in the constant throughput of the channel and/or an increase in the effective latency of the channel. For the video layer, one of the primary considerations is the overall user experience (e.g., the perceptual experience of a user). Video should appear smooth and natural, even under variable network conditions. Under variable channel conditions, providing an acceptable user experience can be particularly challenging for real-time or near real-time video streams, as both packet loss and channel delay can have deleterious effects on perceived video quality (e.g., blocking or blurring effects, video freezing or jerkiness, and audio/video synchronization issues) and, potentially, power consumption in transmitting and receiving devices.
In order to improve utilization of available communication bandwidth for applications such as high definition streamed video, several short-range wireless personal/local area networking standards have emerged in recent years. Many of these technologies exploit high frequency and extremely high frequency radio bands (e.g., 60 GHz). Examples include the Wireless Gigabit Alliance (WGA) WiGig MAC and PHY specification/IEEE 802.11ad, WirelessHD/IEEE 802.15.3c, ECMA 387, Wireless Home Digital Interface (WHDI), and Wireless USB among others.
In addition to MAC/PHY specifications, groups such as WGA have also defined Protocol Adaptation Layers (PALs) that support specific data and display standards over the 60 GHz frequency band, including extensions for computer peripherals and display interfaces for HDTVs, monitors and projectors. For example, the WiGig Display Extension (WDE) specification supports HDMI mapping and wireless connections to DisplayPort monitors and HDMI televisions to enable cable replacement applications such as the wireless transmission of compressed or uncompressed video. The WiGig Bus Extension (WBE) specification enables a wireless version of the PCI Express (PCIe) slot, which provides connections for a wide variety of devices such as video cards and hard drives. Likewise, the Wireless Serial Extension (WSE) specification enables a high-speed serial communications link, providing a wireless version of the USB 3.0 technology. Similar approaches to wireless networking and cable replacement are being developed by other entities and industry groups.